The Púca is from Celtic folklore; a shapeshifter that can take numerous forms (among them horse, goat, dog, eagle or goblin). One form is that of a half-human, half-goat satyr, reminecent of the famous character Puck, from Shakespeare's A Midsummer Night's Dream. Regardless of it's shape, it almost always has dark fur or hair. The most common dipiction of a Púca is that of a sleek black horse with a flowing mane and vibrant yellow eyes.

The Púca could be benevolent, or destructive. As a horse, it would lure people onto it's back and take them away for a wild ride. They would return, but not the same as they left. Accounts differ on whether the Púca, when near lakes or streams, would take the human under the water and rip them apart like kelpies were said to do.

Brian Boru, High King of Irland, used a bridle made of three hairs of the Púca's tail to control and ride it. He rode it until, exhuasted, it succumbed to his will. He forced two promises from it: one, it would no longer harm Christian people or damage their property, and two, it would no longer attack any Irishman unless they were drunk or abroad with evil intent. Apparently, this bargain did not last, since attacks still happened after it was made.

The Púca could speak, and sometimes offered warnings or prophecies to those who left it gifts. It is a creature of the mountains and hills. On November Day, people could ascend to certain high places to leave offerings and seek advice.

Like many of the fairy folk, the Púca was both feared and respected. It enjoyed confusing people, but overall was considered a benevolent creature.